This invention relates generally to the field of interfacing components and, more particularly, to an intelligent module for interfacing an integrated device electronics (IDE) hard disk drive with a modified frequency modulation (MFM)-based control system.
In the mid-1980""s, hard disk drives (herein-after referred to as hard disks) often utilized electrical interfaces compliant with the Institute of Electrical and Electronics Engineers (IEEE) 412 standard. Such hard disks are often referred to as xe2x80x9cdumbxe2x80x9d devices, as they must be told what to do and when to do it (e.g., by a controller). In such a system, physical media is remote from controller electronics, meaning the interface break lies between the mechanical portion of the drive (i.e., the magnetic media, stepper motors, heads, etc.) and the controller electronics.
With hard disks adhering to this standard, signals are transferred from a controller to the hard disk over two separate sets of conductors: a control cable and a data cable. The control cable contains all the necessary signals to select the correct drive, cylinder, and head, as well as status signals from the drive notifying the controller of the location of the sector, index, track 0, drive readiness, etc. Meanwhile, the data cable is used for transmitting differential read and write lines.
Among other schemes, devices adhering to the IEEE 412 standard employed a bit encoding scheme known as Modified Frequency Modulation (xe2x80x9cMFMxe2x80x9d) to store data onto media. In the early 1990""s, however, with the development of the Advanced Technology Attachment (xe2x80x9cATAxe2x80x9d) disk drive interface standard (commonly known as the Integrated Device Electronics (xe2x80x9cIDExe2x80x9d) interface), IEEE 412 technology became obsolete. Thus, advancements in and production of IEEE 412 components, such as MFM hard disks, curtailed, and replacement parts for these components have become increasingly hard to find.
In contrast to xe2x80x9cdumbxe2x80x9d devices, such as MFM hard disks, the controller electronics of an IDE hard disk are moved out with the mechanical portion of the drive, thus changing the drive interface from being between the media and the controller, to being between the controller and the host processor. Therefore, the interfaces for each of these drives are considerably different.
When viewed from an interfacing standpoint, the differences between the two technologies have heretofore made replacing an IEEE 412 component with an IDE component difficult. For example, due to hardware and software constraints, interfacing an IDE hard disk with control systems designed to interface with an MFM hard drive has not been simple or practical for most users. Accordingly, it would be advantageous to provide an apparatus and method that would allow users of IEEE 412 control systems to interface with IDE components, such as IDE hard drives.
It is one object of this invention to provide an IEEE 412 to IDE interface.
It is another object of this invention to provide a simple module capable of interfacing IDE components in systems utilizing an IEEE 412 interface, without the need to change the configuration or the software of the system.
Still another object of the present invention is to provide an intelligent module capable of interfacing with the system while remaining transparent to the system.
Yet another object of this invention is to provide an interface module capable of emulating an interface to an MFM hard disk(i.e., a spinning disk with heads floating over a media surface, a stepper motor cylinder selection, and head and drive selects) when using an IDE hard drive.
According to one embodiment of the present invention, a method for interfacing components is provided. The steps of the method include receiving from a first component a request for an access operation comprising one of at least a write operation and a read operation, the request comprising a requested data address associated with a second component, and determining whether data corresponding to the requested data address is missing from memory, the memory being independent of the second component. When the data is missing from the memory, the method includes the steps of intercepting the request, loading the data from the second component to the memory, and performing the requested access operation. According to such an embodiment, modified data is converted from a first communication type to a second communication type and written to the memory and to the second component during a write operation, and data is converted from the second communication type to the first communication type and read by the first component during a read operation.
In another embodiment of the present invention, a method for writing a serial data stream to a component associated with parallel data streams is provided. This method includes the steps of receiving a serial data stream, converting the serial data stream to a parallel data stream, loading the parallel data stream in memory, and writing the parallel data stream from the memory to a component. Yet another embodiment of the present invention is directed towards a method for reading a serial data stream from a component associated with parallel data streams. The method according to this embodiment includes the steps of receiving a request for data associated with the component, receiving a parallel data stream from memory in response to the request for the data, converting the parallel data stream to a serial data stream, and outputting the serial data stream.
Still other aspects of the present invention will become apparent to those skilled in this art from the following description wherein there is shown and described various embodiments of this invention, simply by way of illustration. As will be realized, the invention is capable of other different aspects and embodiments without departing from the scope of the invention. Accordingly, these exemplary objects are not intended to, nor do they, limit the scope of the present invention in any way, and the drawings and descriptions should be regarded as illustrative in nature and not as restrictive in nature. Further preferred embodiments of the present invention involve a computer readable medium including instructions capable of performing the steps of the various methods of the present invention.